1 Lect 17Digestive Gastrointestinal Tract Accessory Organs Intro to Anatomy , Physiology and Nutrition
2 Digestive Tract = ___________ Mouth Pharynx Esophagus Stomach Small IntestineLarge IntestineAnusAccessory OrgansTeeth and salivary glandsLiver/gall bladderPancreasMesenteriesMouth---bite, chew, swallowPharynx and esophagus----transportStomach----mechanical disruption; absorption of water & alcoholSmall intestine--chemical & mechanical digestion & absorptionLarge intestine----absorb electrolytes & vitamins (B and K)Rectum and anus---defecation
3 Alimentary Canal - Characteristic Cross Section __________ = Passage down the middleMucosaSubmucosaWhat kind of tissue?What is found in this layer?Muscle layerSerosa = ? Type of membrane ____________
5 Functions of the Digestive System The process of taking foods and liquid into the mouth:IngestionThe release of water, acid, buffers, and enzymes by cells and accessory organs into the lumen.SecretionAlternating contraction and relaxation of smooth muscle.Peristalsis Mixing and propulsionMechanical and chemical break down of organic material into small molecules.Digestion
6 Vestibule: space between lips and gums (gingiva)/teeth MouthCheeks: lateral wallsbuccinator muscles, bucal fat padsNon-keratinized stratified squamous epitheliumLips attach to gum: labial frenulum (a midline fold)Vestibule: space between lips and gums (gingiva)/teethOral cavity proper – from gums and teeth to Fauces
8 Oral Cavity Floor: Palate: Tonsils: Mylohyoid muscle Tongue frenulumPalate:Hard Palate: palantine bones + part of maxillaSoft Palate: + Uvula – close oral cavity nasopharynxTonsils:Palatine: either side of tongueLingual : near base of tongue at hyoid bonePharyngeal: = adenoids – posterior wall of pharynx
10 Primary teeth: deciduous – ‘baby teeth’ Adult teeth Fours types:IncisorsCaninesPremolarsMolarsPrimary teeth: deciduous – ‘baby teeth’Adult teethdental formula: number of teeth of each type in one half of each jaw reading from the front (incisors) to back (molars)Humans Adults: 2123/2123
13 Tortora & Grabowski 9/e 2000 JWS Salivary GlandsParotid below your ear and over the masseterSubmandibular is under lower edge of mandibleSublingual is deep to the tongue in floor of mouthAll have ducts that empty into the oral cavityTortora & Grabowski 9/e 2000 JWS
14 Swallowing:What prevents food from entering nasal cavity:What temporarily seals oral cavity/pharynx?What closes opening to respiratory passage?Peristaltic wave pushes _______ down __________.Pharynx – 3 regions:NasopharynxOropharynxLaryngopharynx
15 The Esophagus Anatomy Functions Pierces the diaphragm at hiatus A collapsible 10 inch long muscular tube.FunctionsSecrete mucus and transport food from the pharynx to the stomach.Rhythmic waves of muscle contraction?(Peristalisis).Pierces the diaphragm at hiatushiatal hernia or diaphragmatic herniaThe Esophagus
16 visceral layer covers organs Peritoneumvisceral layer covers organsparietal layer lines the walls of body cavityPeritoneal cavitypotential space containing a bit of serous fluid
17 Greater Omentum- fatty apron: covers transverse colon and small intestine.
18 Falciform Ligament: Suspends liver from anterior wall of abdomen/diaphragm Lesser Omentum: suspends stomach and duodenum from liverMesentary Proper: Extends from dorsal wall of abdominal cavity, suspends small intestineMesocolon: binds transverse and sigmoid colon to dorsal abd. wall
20 Which side is it on?Size when empty?Parts of stomach?Structure of its walls?Smooth muscle layersrugaeGastric pitsWhat digestive processes occur hereAssociated mesenteries?Semifluid contents are known as?
21 Gastric Pits and Gastric Glands Gastric Pits: shallow depressions of gastric mucosaGastric Glands:Open to gastric pitsEndocrine and exocrine cells in wallsExocrine secretions gastric juice
22 Protects walls of stomach Acid environment activates pepsinogenAbsoption o f B12 in small intestineInitiates protein breakdownHormonal activity initiates smooth muscle action and secretion of gastric juice
28 Bile salts act to emulsify Fatty acids + glycerol at villi Absorption of LipidsBile salts act to emulsifyFatty acids + glycerol at villiIntermediate metabolic conversions chylomicrons – protein encased structures enter blood streamDelivered totissues as LDLLiver as HDLBile salts feces
32 Lobes divided into lobules LiverLobes divided into lobulesBlood from portal vein sinusoids central canalMultiple functionsBlood glucose glycogen blood glucoseLipid oxidationFormation of urea from NH2Deamination of aaStorageProduction of bile
36 Large Intestine Regions Functions Cecum Colon – 4 regions Rectum Veriform appendixColon – 4 regionsRectumAnal canalInternal & external anal sphinctersFunctions
37 Symbiotic Bacteria Reside in the Colon Numbers- about 50 species.Fecal component- accounts for about 1/3 the total weight of feces.They are nourished by undigested foods.Their metabolic processes produce gas.Some produce vitamins B and K.They decompose pigmented molecules, which give feces its brown color.
39 Macronutrients – energy source NutritionMacronutrients – energy sourceCalorie – measure of energy in foodsMicronutrients – required for vital biochemical processesIncl. vitamins & mineralsHydrolysis – initial step
40 Essential amino acids (8) Essential nutrientsEssential fatty acidsRequired for synthesis of other forms in liverLinoleic acidEssential amino acids (8)See table 15.8Complete vs partially complete proteins
41 Issues with Fats and Cholesterol 4x amt of energy in carbsDoes Cholesterol intake greatly impact risk of heart disease?What is the impact of intake of different kinds of fats on arthrosclerosis – (linked to heart disease)?Trans fats?